1. Field of the Invention
The present invention relates to a method and apparatus for manufacturing a film with a conductive sheet, for a touch-panel, and a film manufactured thereby.
2. Description of the Related Art
A touch-panel has been used for various devices, by which an operator or a user can input, to the device, signals related to information shown in a display to which the touch-panel is attached. FIG. 7 is a view of a general structure of a touch-panel. In the touch-panel, films with transparent conductive sheets, each being composed of a transparent film 10 of elastic resin and a conductive sheet 20 laminated on the surface of the film 10, are spaced at a small distance via dot spacers 30 so that the conductive sheets 20 are opposed to each other, and are disposed on a glass plate 50. The touch-panel is pressed from the side opposite to the glass plate 50 by a user""s finger or a pen point 40 so that an electrical connection is established at the depressed portion to input information.
FIG. 8 shows an apparatus for manufacturing a film with a transparent conductive sheet, used for the touch-panel. When the film 10, delivered from a delivery roller 100, runs on an intermediate roller 200a, a conductive material is placed on the surface of the film 10 located opposite the roller 200a by sputtering. Then, the film 10 is wound up by a winding roller 300. A cylindrical roller having a uniform diameter is used as the intermediate roller 200a. 
In the touch-panel, a film with a conductive sheet manufactured by applying a conductive material onto the film 10 which is not tensioned, by means of the manufacturing apparatus as mentioned above, is used. Therefore, the conductive sheet 20 is tensioned when it is pressed by a finger or a pen point (see arrows in FIG. 7). Consequently, problems arise in which the conductive sheet 20 cracks or is separated due to repetitive depressions, thus resulting in a malfunction of the touch panel.
In view of the above problems, the object of the present invention is to provide a manufacturing method for easily manufacturing a highly durable film with a conductive sheet which can be used for a touch-panel that works properly for a long time without an occurrence of cracking or separation of the conductive sheet even by repetitive pressing. Another object of the present invention is to provide a manufacturing apparatus for the same and to provide a film manufactured thereby.
According to the present invention, there is provided a method for manufacturing a film having a conductive sheet for a touch-panel, comprising the steps of applying a tensile force to at least a first surface of the film to which a conductive material is to be applied, within its elastic limit; coating the conductive material onto the first surface of the film in a tensioned state; and releasing the tensile force after adhesion of the conductive material.
Preferably, the film is in the form of an elongated strip, and the method comprises the steps of continuously delivering the film and of continuously winding the film to which the conductive material has been applied, wherein, in the tensile force applying step, between the delivering step and the winding step, a second surface, opposite to the first surface to which the conductive material of the film is to be applied, runs on a surface of a barrel-shaped roller whose diameter at a center portion is larger than respective diameters of the end portions while tensioning the film in the travel direction.
Furthermore, according to the present invention, there is provided an apparatus for manufacturing a film having a conductive sheet for a touch-panel, comprising a means for applying a tensile force to at least a first surface of the film to which a conductive material is applied within an elastic limit; a means for coating the first surface of the film in a tensioned state, with the conductive material; and a means for releasing the tensile force.
Preferably, the film is in the form of an elongated strip, and the apparatus comprises a means for continuously delivering the film and a means for continuously winding the film to which the conductive material has been applied, said means for applying a tensile force being composed of a barrel-shaped roller whose diameter at a center portion is larger than respective diameters of the end portions, between the delivering means and the winding means, and a film pulling means for pulling the film in a travel direction so that a second surface opposite to the first surface to which the conductive material of the film is to be applied runs on the surface of the barrel-shaped roller.
Furthermore, according to the present invention, there is provided a film having a conductive sheet for a touch-panel, wherein a conductive material is applied to a first surface as a tensile force is applied to at least the first surface of the film to which the conductive material is to be applied within an elastic limit, and the tensile force is released after the application of the conductive material.
Preferably, while the film, in the form of an elongated strip, is continuously delivered from a delivery roller is tensioned in the travel direction, the film travels on a surface of a barrel-shaped roller whose diameter at a center portion is larger than respective diameters of the end portions, and thereafter the film is wound by a winding roller.
The present invention may be more fully understood from the description of preferred embodiments of the invention set forth below, together with the accompanying drawings: